1. Field of the Invention
This invention relates to a process for preparing 2,6-substituted -9-(1,3-dihydroxy-2-propoxymethyl)purines and certain esters thereof. The invention also relates to novel intermediates useful in the above process and to a process for preparing these intermediates.
2. Related Disclosure
The compounds 9-(1,3-dihydroxy-2-propoxymethyl)-guanine and 2,6-diamino-9-(1,3-dihydroxy-2-propoxymethyl)-purine and certain esters thereof are potent antiviral agents and have been prepared by methods disclosed in U.S. Pat. No. 4,355,032 and European patent applications 49,072; 72,027 and 74,306. The present invention relates to an improved process whereby the side chain intermediate is more stable than known intermediates and is prepared in less steps. One embodiment of the instant invention also eliminates the costly and time consuming hydrogenation step for removal of the protecting benzyl groups from the hydroxy groups on the side chain. Another embodiment of the present invention avoids the chloromethylation step of the known process which yields, as a by-product, bischloromethylether, a known carcinogen. The invention also relates to the novel intermediates and to a method of preparing them.